Design And Fabrication Of Phase-type Supercritical Lens With High Efficiency

The planar diffractive lens has greatly promoted the integrated development of optical lens.Planar matelenses based on matesurface show its light two-dimensional in-plane structure and flexible functional design,but the conventional in-plane phase design is difficult to break through the diffraction limit.In recent years,a series of nearfield and far-field methods to break through the diffraction limit have been reported,but their inherent defects limit their practical application,so it is urgent to develop a pure optical far-field unmarked super-resolution technology.With the development of superoscillation theory,superoscillation/supercritical lens has been widely reported.However,there are still some problems to be solved in the current research work,such as the low efficiency of amplitude superoscillation/supercritical lens,high-order diffraction and secondary focus introduced by binary configuration,complex sample processing,which all limit the application and popularization of superoscillatory/supercritical lens.In view of the above problems,this thesis focuses on the theoretical design of high-efficiency phase type supercritical lens(SCL),new processing methods and the application of lens array.In theoretical design,we establish a theoretical model based on Rayleigh Sommerfeld diffraction integral and particle swarm optimization algorithm,and realize the controllable design of binary phase type single focus and light needle supercritical lens.At the same time,we propose a new type of multi-order phase supercritical lens,which achieves high focusing efficiency and the ability to suppress high-order diffraction and secondary focus obviously.In fabrication,we developed a dual-mode optical lithography technique,synergistically controlling two types of movement trajectory,which is implemented with the piezo stage and the scanning galvo mirror,enables the fabrication of complicated structures with sub-diffraction-limit feature size.By utilizing such advantage,SCLs with binary phase and discretized multilevel phase configurations are explicitly patterned.The experimental characterization results have shown that a binary phase supercritical lens can form a sub-diffraction limit light needle with 6 μm length and a four-level phase SCL can focus light into a sub-diffraction-limit spot with the lateral size of 0.40 λ/NA(NA is the numerical aperture),while achieve the focal spot intensity and the energy concentration ratio in the focal region 7.2 times and 3 times that of the traditional binary amplitude type/phase type SCL with the same optimization conditions,respectively.In microlens arrays(MLAs),we proposed and experimentally demonstrated a high numerical aperture(NA)supercritical lens(SCL)arrays which could achieve subdiffraction limited focal spot lattice in the far field.The intensity distribution for all the focal spots has good uniformity with the lateral size around 0.45 λ/NA(0.75 X airy unit).The elementary unit in the SCL array composes of a series concentric belts with feature size in micrometer scale.By utilizing an ultrafast UV lithography technique,a centimeter scale SCL array could be successfully patterned within 10 mins.The main innovation of this thesis is that we propose the design and processing method of high efficiency phase supercritical lens,and realize the application of centimeter supercritical lens array.Our results may release the application obstacles for the sub-diffraction-limit planar metalens and enable major advances in the fields from label-free optical super-resolution imaging to high precision laser fabrication.